Urticaria is a skin condition that affects 1 in 5 people at certain period of their life. It causes intensely itchy, raised patches on the skin known as weals (or hives) that can be round or ring shaped and may join together.

They often appear after scratching and may affect the skin on every part of the body.

It is caused when histamine and other chemical mediators are released into the bloodstream by certain body cells known as mast cells. The welts are the result of fluid leaking from the skin’s capillaries.

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While the hives usually disappear within 24 hours, the condition itself may take longer to treat.

Urticaria is often accompanied with swelling under the skin known as angio-oedema. This usually affects the soft parts of the body like the lips, eyelids, or inside the mouth.

Unlike hives, these swellings take longer to disappear and are more painful than itchy.

If angio-oedema appears without weals, it could be a hereditary condition called hereditary angio-oedema. In cases like this, it is not connected to urticaria and requires different treatment and blood tests for diagnosis.

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Depending on how long it lasts, urticaria can be categorized into:

Acute urticaria

The most common type of hives is acute urticaria, which refers to a sudden onset of symptoms that generally disappears within six weeks. In almost all instances, the cause of acute urticaria can be pinpointed. Acute urticaria is caused by an allergic reaction or sensitivity that leads to histamines being released into the skin, dilating the blood vessels and causing fluid leakage.

Some of the common triggers include the following:

Allergic Reactions: Bad reaction to any particular food like peanuts, shellfish, eggs, or milk, as well as to insect stings, or even allergies to some substances such as latex.

Medications: Non-steroidal anti-inflammatory drugs (NSAIDs), aspirin, and particular antibiotics, such as penicillin, are common culprits.

Infection: Viral infection like the common cold, hepatitis, or mononucleosis, which is very common in children, or even bacterial infection.

Environmental Factors: Exposure to heat, cold, or emotional stress.

Symptoms usually peak quickly and fade within a few days or weeks, responding well to oral antihistamines.

Chronic urticaria

The chronic form of urticaria is characterized by repeated outbreaks of wheals and hives on a frequent basis, usually on a daily basis, for more than six weeks. In contrast to acute urticaria, it is particularly challenging to identify the precise trigger for chronic urticaria, which is unknown in as many as 80% to 90% of cases.

Key characteristics and underlying mechanisms include:

Autoimmune Connection: It is estimated that in approximately half of the cases, the body’s own immune system attacks the body’s tissues. Elevated levels of autoantibodies bind to IgE receptors on the mast cells resulting in histamine secretion.

Underlying Conditions: There are times when chronic hives result from a systemic condition in the body. Some examples include hypothyroidism, lupus, and rheumatoid diseases.

Quality of Life Implications: Since individual lesions resolve themselves within a span of 24 hours but new lesions keep cropping up somewhere else, this disorder may lead to sleep disturbances and emotional turmoil. Therapy for this disorder entails aggressive treatment options such as high doses of antihistamines, biologics (such as omalizumab), or immunosuppressives.

Physical Urticaria

Physical urticaria, which may also be known as inducible urticaria, represents a special type of hives in which the formation of lesions on the skin results from exposure to a particular external agent, not any internal factors. The hives occur promptly, within a minute or two after being triggered and are restricted to the part of the skin contacted.

Some of the most frequent triggers are:

Dermographism (Skin Writing): Raised, itchy hives resulting from the physical stimulation of the skin through friction, scratching, or pressing hard on the skin surface. Any light scratching may leave itchy, elevated marks on the skin.

Cold Urticaria: This occurs due to sudden contact with cold air, cold water, or ice. If the whole body is immersed in cold water, it might turn life-threatening by causing a generalized release of histamine.

Cholinergic Urticaria (Heat/Urine): Caused by an increase in body heat. It may occur during exercise, bathing in hot water, eating spicy foods, or intense mental stress.

Solar Urticaria: A unique type that is caused by contact with ultraviolet (UV) rays or natural sunlight.

Delayed Pressure Urticaria: Results from prolonged and heavy pressure applied to the skin for hours—for instance, carrying heavy backpack straps, sitting in an uncomfortable position, or tightening one’s belt. This condition is different from other forms of physical urticaria because it takes up to 4–8 hours for symptoms to occur and feels deeper and more painful than itchy.

Though hives are generally harmless, there are times when waiting it out is not an option. If your hives are accompanied by breathing difficulties such as shortness of breath, swelling of the tongue or throat, dizziness, or chest tightness, immediate medical attention should be sought. These symptoms may indicate an anaphylactic reaction, which can be life-threatening.

To help identify possible triggers, your doctor may recommend keeping a symptom diary. While it may seem time-consuming, recording the foods you eat, medications you take, stress levels, daily activities, and the timing of outbreaks can help uncover patterns and possible causes behind the hives.

There are also certain lifestyle changes that may help reduce flare-ups. These include wearing loose-fitting clothing, using fragrance-free skincare products instead of harsh soaps, keeping the skin cool, and taking steps to manage stress. For itchy outbreaks, applying a cool compress may provide immediate relief.

Living with chronic hives can feel overwhelming, especially when the flare-ups keep returning, but many cases can be managed successfully once the right treatment plan is found and the person understands their triggers. It is important to consult a healthcare professional if symptoms become severe, frequent, or begin interfering with quality of life.